Hi Ross,
Due to general lack of interest for a full tenancy management feature (and the amount of work involved), it's been agreed to not continue development on this feature.
What we found that most users are actually just looking to hide certain content (courses/assets/plugins etc.) from groups of users. To this end, we're going to be adding a 'user groups' feature to the v1.0.0 authoring tool which will allow admins to create groups of users, and assign content visibility to those groups. Once the v1.0.0 stable release is publicly available, this will be one of the first new additions.
This differs slightly from true multitenancy, which is more concerned with a physical separation of data (separate databases, separated folder structure), usually for data privacy reasons. Users looking for this kind of approach are better off running multiple instances of the authoring tool for true separation (very little extra overhead, and much more simplicity).
Hopefully this clears things up!